1. Field of the Invention
The present invention relates to magnetic disk apparatuses in which a magnetic disk is loaded and used, and more particularly, to a magnetic disk apparatus which reduces abrasion caused by a head on a disk surface.
2. Description of the Related Art
Magnetic media such as floppy disks have been used in magnetic disk apparatuses for recording computer data. In recent years, magnetic media with high capacities have been introduced.
In a conventional magnetic disk apparatus, when data is recorded into or reproduced from a medium, a head contacts the medium while the medium is rotating. Even after data recording or reproduction is finished, the head continues to contact the rotating medium.
Therefore, in some magnetic disk apparatuses for high-capacity media, when data recording or reproduction is not performed for a predetermined period of time, the head is moved to a position where a scratch on a medium causes no problem, namely, to an area not to be used on the disk, for example, to the innermost or the outermost side of the disk.
In such a conventional magnetic disk apparatus, however, when data recording or reproduction into or from a medium is requested from the host computer after the head is moved to an area not to be used on the disk, it takes a long time to perform recording or reproduction. To solve this problem, if the head is retracted after a longer time elapses, the probability that the medium will become abraded increases.
In other words, as shown in FIG. 4, even when data is not recorded or reproduced, a head 4 is driven by a driving section 20 that supports the head to compensate for a positional error, and a current flows into the section. If the head 4 vibrates or a mechanical resonance of the head 4 and a suspension 30 occurs, driving the driving section 20 greatly increases the vibration. As a result, abrasion of the medium 1 occurs.
In some magnetic disk apparatuses for high-capacity media, when data recording or reproduction is not performed, a measure is taken in which the head is reciprocated around the target track in order that the same track is not abraded for a long period.
In such a magnetic disk apparatus, however, although abrasion is averaged on the medium 1, a response to a R/W command sent from the user is delayed. If the head vibrates by a small amount in order to solve this problem, a quick response is obtained but the effect of abrasion averaging becomes less effective.
As described above, in the conventional magnetic disk apparatus, the probability that the medium abrades increases an, in the worst case, previously recorded data may be damaged. The period in which the medium can be used becomes short and the medium frequently needs to be replaced with a new one to avoid data loss.
An additional problem is that power consumption is large even when data reading or writing is not performed, since the head is being driven.